This week the search warrants related to the investigation of Michael Cohen, President Donald Trump’s personal attorney, were unsealed. There is a treasure trove of tantalizing information in the 897 pages of documents released for public consumption.

One issue tucked away in a search warrant executed on April 8, 2018, deserves some attention. The warrant authorized investigators to “employ an electronic investigation technique” to locate two cell phones used by Cohen.

The FBI used a secret cell phone sweeping device to pinpoint Cohen’s location in New York City.

The device, known as a Stingray, tricks cell phones into sending their location information to the device that simulates a cell phone tower. The device tracked Cohen’s two cell phones to a pair of hotel rooms in Manhattan where he was temporarily residing with his family.

According to CBS News, it is not clear exactly what additional information law enforcement obtained from the Stingray. The device is also capable of collecting calls, text messages and even emails sent to and from cell phones.

However, the Stingray doesn’t just collect data from the target of an investigation. The device is capable of gathering information from multiple cell phone users throughout an entire neighborhood, building or, as in this case, a hotel. The increasing use of the Stingray has alarmed privacy rights groups.

If a Stingray is deployed without Court approval, the result may be a violation of the Fourth Amendment right to be free from unreasonable searches.

The Washington Post reported that Courts in Washington, D.C., Maryland, New York and California have ruled that using a Stingray without first obtaining a search warrant violates the Constitution.

The Federal Court of Appeals in Washington, D.C. excluded evidence in a criminal case which utilized Stingray technology without a search warrant. Judge Corinne A. Beckwith wrote, “Locating and tracking a cell-site simulator has the substantial potential to expose the owner’s intimate personal information.”

“A (Stingray) allows police officers who possess a person’s telephone number to discover that person’s precise location remotely and at will,” continued Beckwith.

The United States Supreme Court has reviewed technology used to locate a suspect by tracking the pings from a cell phone to a cell tower. “We decline to grant the state unrestricted access to a wireless carrier’s database of physical location information,” wrote Chief Justice John G. Roberts Jr. in 2018.

According to the Washington Post, the Court’s 5-to-4 ruling protects “deeply revealing” records from more than 400 million devices. The Constitution must take account of changes in technology, Roberts wrote, noting that digital data can provide a comprehensive, detailed - and intrusive - overview of private affairs that would have been impossible to imagine not long ago.

The Supreme Court made exceptions for emergencies like bomb threats and child abductions. “Such exigencies,” Roberts wrote, “include the need to pursue a fleeing suspect, protect individuals who are threatened with imminent harm or prevent the imminent destruction of evidence.” Those are the same emergency exceptions that exist for entering a home or dwelling without a search warrant.

In addition, Cohen investigators wanted the search warrant sealed because of the secret nature of the Stingray. The secrecy is not unique to the Cohen investigation. According to CBS News, the government has, in the past, withdrawn charges against criminal defendants rather than reveal information about the use of a Stingray.

As a result, it's unknown how often Stingray technology is used. As reported by CBS News, the ACLU found 14 federal agencies that use the device and cataloged Stingray use by 75 agencies in 27 states and the District of Columbia.

Stingray technology is here to stay. Fortunately, the shroud of secrecy has been lifted and courts have begun to formulate appropriate protections.

Matthew T. Mangino is of counsel with Luxenberg, Garbett, Kelly & George P.C. His book The Executioner’s Toll, 2010 was released by McFarland Publishing. You can reach him at www.mattmangino.com and follow him on Twitter @MatthewTMangino.